code: def _nullify_batch_norm():
      """
      Replaces all the BatchNorm with :class:`torch.nn.Identity`.
      Args:
          module: BatchNorm module to be replaced
  
      Returns:
          InstanceNorm module that can replace the BatchNorm module provided
  
      Notes:
          Most of the times replacing a BatchNorm module with Identity
          will heavily affect convergence of the model.
      """
      return nn.Identity()
  
file_path: opacus/opacus/validators/batch_norm.py
imports: import logging
  import math
  from typing import List, Optional, Union
  import torch.nn
  from .errors import ShouldReplaceModuleError, UnsupportableModuleError, UnsupportedModuleError
  from .utils import register_module_fixer, register_module_validator
label_desc: Use image node_id 5 for calling a global function with example usage: _nullify_batch_norm() and returns: nn